SRM-5A

Name: SRM-5A
Brand: Campbell Scientific
SKU: 10694
Availability: Discontinued

Short Haul Modem

SRM-5A

Retired

Short Haul Modem

Pricing

Model:: SRM-5A
Item Number:: 10694
Warranty:: 1 year
Compliance:: price for each modem; 2 required

Overview

SRM-5A RAD Short Haul Modem

The SRM-5A, manufacted by RAD, is an asynchronous modem used for local communication between a data logger and a computer. Two SRM-5A Short Haul Modems are required: one at the data logger end and one at the computer end. Each short haul modem transmits over an unconditioned 4-wire telephone line or the CABLE2TP two-twisted pair cable. Data rates up to 9,600 bps are possible.

Technical Description

Campbell Scientific recommends connecting the SRM-5A to the data logger's CS I/O port via the SC932A interface; a 9-to-25 pin adapter is required. It may be possible to connect the SRM-5A to the data logger's RS-232 port, but configuration is more complicated; contact Campbell Scientific for more information. Surge protectors on both ends of the transmission line are strongly recommended.

Approximate Range with Various Data Rates and Wire Gage

Wire Gage	9600 bps Data Rate	1200 bps Data Rate
19 Gage (0.9 mm)	10.0 km (6.2 miles)	12.2 km (7.6 miles)
24 Gage (0.5 mm)	4.5 km (2.8 miles)	2.8 km (3.4 miles)
26 Gage (0.4 mm)	3.3 km (2.0 miles)	4.0 km (2.5 miles)

Power Requirements

At Computer: uses low power from the EIA RS-232-C/CCITT V.24 data and control signals
At Data logger: combined current drain of the SC932A and RAD modem, which is 2.2 mA quiescent, and 10 to 15 mA active
Protection: ac/dc over voltage connected via isolation transformers rated at 1,500 V RMS

Benefits

Provides the easiest link for communicating with one data logger over longer distances
Low voltage transmission levels minimize crosstalk between adjacent lines within the same cable.
Data are transmitted and received at a balanced impedance, providing excellent immunity to circuit noise.
Transmits up to 6.2 miles using 19 gauge cable at 9600 bps
Transmits up to 7.6 miles at 1200 bps

Specifications

Data Rates: Up to 9,600 bps
Transmission Mode: Asynchronous, full duplex, 4-wire operation
Transmission Distance or Area: Up to 12.2 km
(7.6 mi) depending on data rate and wire gage
Line Interface: 5-screw (4-wire and ground) connector block with cable strain relief inside plastic cover
Transmission Line: CABLE2TP (for short RS-232 or prewired enclosures) or unconditioned, 4-wire telephone line
Transmission Level: 6 dBm
Terminal Interface: EIA RS-232-C/CCITT V.24, female integral 25-pin connector
Operating Temperature Range: 0° to 60°C
(Manufacturer's temperature specification is listed. Limited tests conducted by Campbell Scientific have shown the SRM-5A to perform at temperatures over -25° to +50°C.)
Current Drain at 12 Vdc: 2.2 mA
(quiescent)
Current Drain at 12 Vdc: 10 to 15 mA
(active)
Altitude: Up to 3,000 m
(10,000 ft)
Humidity: Up to 95%
(non-condensing)
Service Requirements: Dedicated two-twisted pair cable connects one field station with base.
Dimensions: 5.2 x 5.2 x 1.8 cm
(2.1 x 2.1 x. 0.7 in.)
Weight: 38 g
(1.3 oz)

Accessories

(9)